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// Copyright 2011 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/memory/weak_ptr.h"
#if DCHECK_IS_ON()
#include <ostream>
#include "base/debug/stack_trace.h"
#endif
namespace base::internal {
WeakReference::Flag::Flag() {
// Flags only become bound when checked for validity, or invalidated,
// so that we can check that later validity/invalidation operations on
// the same Flag take place on the same sequenced thread.
DETACH_FROM_SEQUENCE(sequence_checker_);
}
void WeakReference::Flag::Invalidate() {
// The flag being invalidated with a single ref implies that there are no
// weak pointers in existence. Allow deletion on other thread in this case.
#if DCHECK_IS_ON()
std::unique_ptr<debug::StackTrace> bound_at;
DCHECK(sequence_checker_.CalledOnValidSequence(&bound_at) || HasOneRef())
<< "WeakPtrs must be invalidated on the same sequenced thread as where "
<< "they are bound.\n"
<< (bound_at ? "This was bound at:\n" + bound_at->ToString() : "")
<< "Check failed at:";
#endif
invalidated_.Set();
}
bool WeakReference::Flag::IsValid() const {
// WeakPtrs must be checked on the same sequenced thread.
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
return !invalidated_.IsSet();
}
bool WeakReference::Flag::MaybeValid() const {
return !invalidated_.IsSet();
}
#if DCHECK_IS_ON()
void WeakReference::Flag::DetachFromSequence() {
DETACH_FROM_SEQUENCE(sequence_checker_);
}
void WeakReference::Flag::BindToCurrentSequence() {
DETACH_FROM_SEQUENCE(sequence_checker_);
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
}
#endif
WeakReference::Flag::~Flag() = default;
WeakReference::WeakReference() = default;
WeakReference::WeakReference(const scoped_refptr<Flag>& flag) : flag_(flag) {}
WeakReference::~WeakReference() = default;
WeakReference::WeakReference(const WeakReference& other) = default;
WeakReference& WeakReference::operator=(const WeakReference& other) = default;
WeakReference::WeakReference(WeakReference&& other) noexcept = default;
WeakReference& WeakReference::operator=(WeakReference&& other) noexcept =
default;
void WeakReference::Reset() {
flag_ = nullptr;
}
bool WeakReference::IsValid() const {
return flag_ && flag_->IsValid();
}
bool WeakReference::MaybeValid() const {
return flag_ && flag_->MaybeValid();
}
WeakReferenceOwner::WeakReferenceOwner()
: flag_(MakeRefCounted<WeakReference::Flag>()) {}
WeakReferenceOwner::~WeakReferenceOwner() {
flag_->Invalidate();
}
WeakReference WeakReferenceOwner::GetRef() const {
#if DCHECK_IS_ON()
// If we hold the last reference to the Flag then detach the SequenceChecker.
if (!HasRefs()) {
flag_->DetachFromSequence();
}
#endif
return WeakReference(flag_);
}
void WeakReferenceOwner::Invalidate() {
flag_->Invalidate();
flag_ = MakeRefCounted<WeakReference::Flag>();
}
void WeakReferenceOwner::BindToCurrentSequence() {
#if DCHECK_IS_ON()
flag_->BindToCurrentSequence();
#endif
}
WeakPtrFactoryBase::WeakPtrFactoryBase(uintptr_t ptr) : ptr_(ptr) {
DCHECK(ptr_);
}
WeakPtrFactoryBase::~WeakPtrFactoryBase() {
ptr_ = 0;
}
} // namespace base::internal
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